Expanded IPosition for shapes. More...

#include <TSMShape.h>

Public Member Functions
	TSMShape ()
	A zero-length TSMShape.
	TSMShape (const IPosition &shape)
	Construct from a shape and precalculate some values.
	TSMShape (const TSMShape &that)
	Copy constructor (copy semantics).
TSMShape &	operator= (const TSMShape &that)
	Assignment (copy semantics).
	~TSMShape ()
Int	operator() (uInt index) const
	Index into the TSMShape.
uInt	nelements () const
	The number of elements in this TSMShape.
Bool	conform (const TSMShape &other) const
	conform returns true if nelements() == other.nelements().
size_t	offset (const IPosition &position) const
	Calculate the offset for a given position.
size_t	offset (const IPosition &position, const IPosition &origin) const
IPosition	position (size_t offset) const
	Calculate the position for a given offset.
IPosition	position (size_t offset, const IPosition &origin) const
IPosition	offsetIncrement (const IPosition &subShape) const
	Calculate the increments when stepping through an array in a linear way.
IPosition	offsetIncrement (const IPosition &subShape, const IPosition &stride) const
Private Attributes
IPosition	data_p

uInt	size_p

Detailed Description

Expanded IPosition for shapes.

Intended use:

Internal

Review Status

Reviewed By:: UNKNOWN
Date Reviewed:: before2004/08/25

Prerequisite

IPosition

Etymology

TSMShape handles the shapes for the Tiled Storage Manager.

Synopsis

TSMShape is an extension of class IPosition to handle shapes. It contains some precalculated values to speed up the calculation of an array offset from an array index (and vice-versa).

Motivation

The Tiled Hypercube Storage Manager is heavily using array shapes and determining offsets from array indices. This class makes these calculations more efficient.

To Do

Integrate in a class like LatticeLayout.

Definition at line 77 of file TSMShape.h.

Constructor & Destructor Documentation

casa::TSMShape::TSMShape ( )

A zero-length TSMShape.

casa::TSMShape::TSMShape ( const IPosition & shape )

Construct from a shape and precalculate some values.

casa::TSMShape::TSMShape ( const TSMShape & that )

Copy constructor (copy semantics).

casa::TSMShape::~TSMShape ( )

Member Function Documentation

Bool casa::TSMShape::conform ( const TSMShape & other ) const [inline]

conform returns true if nelements() == other.nelements().

Definition at line 174 of file TSMShape.h.

References casa::IPosition::conform(), and data_p.

uInt casa::TSMShape::nelements ( ) const [inline]

The number of elements in this TSMShape.

Since TSMShape objects use zero-based indexing, the maximum available index is nelements() - 1.

Definition at line 164 of file TSMShape.h.

References size_p.

size_t casa::TSMShape::offset ( const IPosition & position ) const

Calculate the offset for a given position.

size_t casa::TSMShape::offset	(	const IPosition &	position,
		const IPosition &	origin
	)		const

IPosition casa::TSMShape::offsetIncrement ( const IPosition & subShape ) const

Calculate the increments when stepping through an array in a linear way.

This can be used to update the array offset without recalculating it after each step. For example:

        template<class T>
        Array<T> someFunc (const Array<T>& array,
                           const IPosition& subArrayShape,
                           const IPosition& subArrayStart) const
        {
            TSMShape TSM (array.shape());
            IPosition offsetIncr = TSM.offsetIncrement (subArrayShape);
            Array<T> subArray(subArrayShape);
            Bool deleteMain;
            const T* mainData = array.getStorage (deleteMain);
            mainData += TSM.offset (subArrayStart)
            Bool deleteSub;
            T* subData = subArray.getStorage (deleteSub);
            for (uInt i=0; i<subArrayShape(2); i++) {
                for (uInt j=0; j<subArrayShape(1); j++) {
                    for (uInt k=0; k<subArrayShape(0); k++) {
                        *subData++ = *mainData++;
                    }
                    mainData += offsetIncr(1);
                }
                mainData += offSetIncr(2);
            }
        }

IPosition casa::TSMShape::offsetIncrement	(	const IPosition &	subShape,
		const IPosition &	stride
	)		const

Int casa::TSMShape::operator() ( uInt index ) const [inline]

Index into the TSMShape.

Indices are zero-based. If the preprocessor symbol AIPS_ARRAY_INDEX_CHECK is defined, "index" will be checked to ensure it is not out of bounds. If this check fails, an AipsError will be thrown.

Definition at line 169 of file TSMShape.h.

References data_p.

TSMShape& casa::TSMShape::operator= ( const TSMShape & that )

Assignment (copy semantics).

"this" and "that" must either be conformant (same size) or "this" must be 0-length, in which case it will resize itself to be the same length as "that".

IPosition casa::TSMShape::position ( size_t offset ) const

Calculate the position for a given offset.